Oral Presentation Lorne Infection and Immunity 2019

Immune reconstitution and antiviral drug resistance in haematopoietic stem cell transplant recipients with reactivated human cytomegalovirus infection (#15)

Lauren Stern 1 , Selmir Avdic 2 3 4 , Nicolas Suarez 5 , Helen McGuire 6 7 , Caryn Van Vreden 6 , Allison Abendroth 1 , David Gottlieb 2 3 4 , Andrew Davison 5 , Emily Blyth 2 3 4 , Barry Slobedman 1
  1. Discipline of Infectious Diseases and Immunology, University of Sydney, Sydney, NSW, Australia
  2. Sydney Cellular Therapies Laboratory, Westmead, NSW, Australia
  3. Blood and Marrow Transplant Unit, Westmead Hospital, Westmead, NSW, Australia
  4. Westmead Institute for Medical Research, Westmead, NSW, Australia
  5. Centre for Virus Research, University of Glasgow, Glasgow, Scotland
  6. Ramaciotti Facility for Human Systems Biology, University of Sydney, Camperdown, NSW, Australia
  7. Discipline of Pathology, University of Sydney, Camperdown, NSW, Australia

Allogeneic haematopoietic stem cell transplantation (HSCT) is a potentially curative therapy for a range of haematological malignancies and non-malignant disorders of the bone marrow. The success of HSCT depends on effective reconstitution of a donor-derived immune system after transplantation, which is critical for protecting transplant recipients from opportunistic infections and relapse. Human cytomegalovirus (HCMV) reactivation is the leading infectious complication after HSCT, arising in up to 80% of latently-infected patients and often leading to life-threatening disease.

We sought to determine whether profiles of immune reconstitution after HSCT might be associated with protection from or predisposition to HCMV reactivation. Peripheral blood samples were collected from HSCT recipients at multiple time points during the first 100 days post-transplant and mass cytometry (CyTOF) used to track reconstitution of multiple immune cell populations at time-points preceding, during and following HCMV reactivation. Prior to detection of reactivation, elevated proportions of activated T cells, PD-1+ T cells and CD16+ NK cells were found in patients who subsequently developed reactivation, compared to those without reactivation. In addition, expanded percentages of CD8+ T cells and diminished B cell proportions were observed at the peak of reactivation, indicating a potential influence of viral reactivation on immune reconstitution in the early period post-HSCT.

We also sought to define the evolution of antiviral drug resistance mutations in HSCT recipients with reactivation who were treated with HCMV-specific T cells (ie adoptive T cell therapy; ACT) and a variety of HCMV antiviral drugs. Using a target enrichment protocol coupled with high-throughput sequencing, we derived whole HCMV genome sequence data at multiple times post ACT and identified a high degree of plasticity in the emergence of antiviral drug resistance mutations, together with other mutations not previously associated with antiviral drug resistance.

These studies combining the power of mass cytometry and whole viral genome sequencing across multiple samples from HSCT recipients may help to better predict HCMV reactivation and guide the administration of antiviral therapies.